Valves, including plug valves, have been used as a means for reliable flow isolation in high pressure flow line applications. Problems, however, exist with respect to the sealing capability of these devices when used in connection with fluids containing abrasive materials. The present invention relates to the sealing problems at the interface of the rotatable member found in such valves and their respective valve seats.
Prior attempts to seal the interface between the rotatable member and seats found in plug valves have included placement of O-rings within grooves located in the face of the plug or the body of the valve itself. The O-ring design, as well as reliance on other gasket-type sealing devices, results in valve seal failure when used in high pressure environments (e.g., 10,000 to 15,000 psi) containing abrasive matter. Industry standards require that valves used in high pressure applications operate within permissible pressure ranges with minimal permissible levels of leakage. When operating in a high pressure environment, abrasive materials, such as sand, abrade the inner surface of the valve body and plug, including any grooved areas. As the inner surface is abraded, the interference fit between the valve and valve seats is decreased thereby lessening the sealing capability of the valve. Valves must be tested on a regular basis and if they do not pass inspection, they must be replaced resulting in undesirable costs and lost work hours and efficiency during the replacement of the valve.
A need exists, therefore, for improved systems and methods for valve refurbishment and/or strengthening of valves to improve the sealing function and decrease maintenance costs and lost time associated with valve failure.